Piston-type water pump

ABSTRACT

A pump apparatus is provided comprising: a housing; a water chamber in the housing; an hydraulic chamber in the housing; a rod member extending at least partially into each of the water chamber and the hydraulic chamber; a first piston member mounted on the rod member and contained within the hydraulic chamber; a second piston member mounted on the rod member and contained within the water chamber; hydraulic means for alternatively forcing the first piston member in first and second directions; fluid inlet means extending through the housing adjacent an end of the water chamber; and fluid outlet means extending through the housing adjacent the end of the water chamber; wherein when the hydraulic means force the first piston member to move in the first direction, the second piston member is forced to move in the first direction, and fluid is drawn through the fluid inlet means into the water chamber; and wherein when the hydraulic means force the first piston member to move in the second direction, the second piston member is forced to move in the second direction, and fluid is forced through the fluid outlet means.

FIELD OF THE INVENTION

The present invention relates to water pumps, and more particularly towater pumps that can be employed in the petroleum industry.

BACKGROUND OF THE INVENTION

Water pumps are currently used in the petroleum industry for a varietyof purposes, for example dewatering applications in coalbed methanewells. Coalbed methane gas is a form of natural gas that is trapped innaturally-fractured coal seams, a low pressure, water-saturatedenvironment. Removing the water trapped in the coal seams reduces theformation pressure and accordingly allows the trapped gas to desorb fromthe coal seams and flow to the wells. Typically, large volumes of waterare produced during the early stages of production and the initial gasproduced from the coalbed wells is modest, a period which can last up tothree years in some cases. The dewatering period depends on such factorsas coal seam permeability and well spacing, but in-well pumping can alsoaffect the dewatering period. As the dewatering of the coal continues,the gas rates typically increase, so dewatering of the coal seams iscrucial for production operations.

Standard water pumps used in the petroleum industry for coalbeddewatering applications pump the water up like a common water pump,using sucker rods on the surface to push and pull the plunger. Standardwater pumps commonly used for such purposes require a service rig forinstallation, and they can take approximately 1-1½ days to fit the unit.A standard unit also requires the presence of a cement pad base and theuse of a crane truck to load and unload the unit onsite, as well as anadditional separate well casing to extract the water to the surface.Common screw-type pumps have a drive on the surface with a drive linefrom surface to the screw-type pump at the bottom of the well, toperform the required functions. In addition to these service andinstallation disadvantages, there are associated disadvantages regardingcontrol of the standard pump unit. Depending on the speed of movement,the plunger can sometimes buckle inside the well. Also, there is limitedcontrol of speed and volume as the system has to be closely monitored toprevent plug-ups and component damage. Further, manufacture of thejoints in the inner casing and also the joints on the sucker rods forpushing/pulling is relatively costly.

SUMMARY OF THE INVENTION

According to one aspect of the present invention there is provided apump apparatus comprising: a housing; a water chamber in the housing; anhydraulic chamber in the housing; a rod member extending at leastpartially into each of the water chamber and the hydraulic chamber; afirst piston member mounted on the rod member and contained within thehydraulic chamber; a second piston member mounted on the rod member andcontained within the water chamber; hydraulic means for alternativelyforcing the first piston member in first and second directions; fluidinlet means extending through the housing adjacent an end of the waterchamber; and fluid outlet means extending through the housing adjacentthe end of the water chamber; wherein when the hydraulic means force thefirst piston member to move in the first direction, the second pistonmember is forced to move in the first direction, and fluid is drawnthrough the fluid inlet means into the water chamber; and wherein whenthe hydraulic means force the first piston member to move in the seconddirection, the second piston member is forced to move in the seconddirection, and fluid is forced through the fluid outlet means.

In preferred embodiments of the present invention, the hydraulic meanscomprise: a first hydraulic tube in fluid communication with theinterior of the hydraulic chamber on a first side of the first pistonmember; and a second hydraulic tube in fluid communication with theinterior of the hydraulic chamber on a second, opposite side of thefirst piston member; wherein when hydraulic fluid is forced through thefirst hydraulic tube, the first piston member is forced to move in thefirst direction; and wherein when hydraulic fluid is forced through thesecond hydraulic tube, the first piston member is forced to move in thesecond direction.

In further preferred embodiments, this fluid outlet means comprise afluid exhaust passage within the housing; the fluid inlet means andfluid outlet means comprise check valves to control fluid flow; and thefluid inlet means comprise an aperture opening in a downstreamdirection, such that when the fluid is drawn through the fluid inletmeans into the water chamber, the fluid is drawn in an upstreamdirection to avoid undue fines and gals build-up in the fluid inletmeans. The unit is also preferably made of stainless steel.

The present invention therefore seeks to provide a piston-type waterpump that can more effectively perform the same type of work for whichthe standard water pump is currently employed, with greater control anddecreased manufacturing costs.

A pump apparatus in accordance with the present invention can beinstalled using a coiled tubing rig, taking approximately ½ to 1 day tofit the unit, an installation time savings of approximately 40% over thestandard pump units. A pump apparatus according to the present inventioncan also be used with a self-contained power unit, which can begas-powered or electric depending on what is available onsite. Inaddition, a pump apparatus according to the present invention can bedelivered on a one-ton flatbed truck and can be loaded and unloadedonsite using the crane on the tubing truck where a coil tubinginstallation is employed.

The pump apparatus is preferably suspended by three endless tubes fromthe surface to the pump, the apparatus being set at the bottom of awell. Two of the tubes would then contain hydraulic oil, which hydraulicoil drives the piston, one of the tubes forcing the piston up and thenthe other tube forcing the piston down. When the piston is forced down,water is drawn in through a check valve in the water chamber. When therod is at the end of its stroke a pressure signal is sent to the powerunit, the piston is forced up by means of the other tube, the suctioncheck valve closes, and water is pushed through a fluid exhaust tube tothe surface until a pressure signal is received and the piston is oncemore forced down to refill the water chamber.

Due to the fact that this unit is preferably made of stainless steel,and there are few internal parts, there is less chance for contaminationand breakdowns when compared to the standard pump units currently inoperation. In terms of control, a pump apparatus according to thepresent invention can provide greater control of the system speed andvolume, with little stress to the pump unit. The slower the speed, theless water is pumped, while increasing the speed results in a greatervolume of water being pumped.

A detailed description of an exemplary embodiment of the presentinvention is given in the following. It is to be understood, however,that the invention is not to be construed as limited to this embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings, which illustrate an exemplary embodimentof the present invention:

FIG. 1 is a top plan view of a pump apparatus according to the presentinvention, showing the positioning of the water exhaust tube andhydraulic supply tubes;

FIG. 2 is a side elevation view of the downstream end of a pumpapparatus according to the present invention, showing the connectors forthe hydraulic supply tubes;

FIG. 3 is a side elevation view of the next section of the pumpapparatus of FIG. 2, connected to the upstream end of the section ofFIG. 2, showing the water intake and exhaust means;

FIG. 4 is a side elevation view of the next section of the pumpapparatus of FIG. 2, connected to the upstream end of the section ofFIG. 3, showing the piston in the water chamber; and

FIG. 5 is a side elevation view of the upstream section of the pumpapparatus of FIG. 2, connected to the upstream end of the section ofFIG. 4, showing the piston in the hydraulic chamber.

DETAILED DESCRIPTION OF AN EXEMPLARY EMBODIMENT

Referring now in detail to the accompanying drawings, there isillustrated an exemplary embodiment of a pump apparatus according to thepresent invention, generally referred to by the numeral 10. The pumpapparatus 10 comprises a housing 12, which houses a water chamber 14(shown in FIGS. 3 and 4) and an hydraulic chamber 16 (shown in FIG. 5).In the preferred embodiment, the water chamber 14 is adjacent anddownstream of the hydraulic chamber 16, although other configurationsare possible.

Referring now in detail to FIGS. 4 and 5, a stainless steel rod 18extends partially into the water chamber 14 at one end, and its oppositeend extends partially into the hydraulic chamber 16. Mounted on the rod18, within the water chamber 14, is a water piston 22 (which isstainless steel and may be provided with molded urethane), secured bymeans of a lock nut 66 and in contact with an oil-impregnated bronzewear ring 70, which water piston 22 reciprocates within the waterchamber 14 in response to movement of the rod 18. Mounted on the rod 18,within the hydraulic chamber 16, is an hydraulic piston 22, secured bymeans of a lock nut 68, which reciprocates within the hydraulic chamber16 in response to the influence of the hydraulic system (discussedbelow), driving the movement of the rod 18.

First and second hydraulic supply tubes 28, 30 (shown in FIG. 1) arehoused within a hollowed out section of the housing 12. First and secondhydraulic supply tubes 28, 30 pass along the length of the housing 12until they connect with the downstream side of connectors 40 on thehousing 12, as can be seen in FIG. 2, and pass from the upstream side.The hydraulic supply tubes 28, 30 are threaded into the connectors 40for stability, and they are preferably held against the housing 12exterior by means of hose clamps (not shown). The sections of thehydraulic supply tubes 28, 30 upstream of the connectors 40 pass down tothe upstream section of the pump apparatus 10, as can be seen in FIG. 5.The first hydraulic supply tube 28 is threaded into connector 42, with afinal section of first hydraulic supply tube 28 being threaded betweenconnectors 44 and 46. The result is that first hydraulic supply tube 28can supply hydraulic fluid (not shown) into a portion of the hydraulicchamber 16 downstream of the hydraulic piston 20, driving the hydraulicpiston 20 in an upstream direction. The second hydraulic supply tube 30passes parallel to the first hydraulic supply tube 28 until it reachesthe upstream section of the pump apparatus 10. The second hydraulicsupply tube 30 is threaded into a connector 48, and is used to supplyhydraulic fluid to a portion of the hydraulic chamber 16 upstream of thehydraulic piston 20, driving the hydraulic piston 20 in a downstreamdirection. By alternating supply of hydraulic fluid to the first andsecond hydraulic supply tubes 28, 30, the hydraulic piston 20 can beselectively forced in upstream and downstream directions within thehydraulic chamber 16.

As the hydraulic piston 20 is mounted on the rod 18, movement of thehydraulic piston 20 drives the rod 18 in the same direction. This causesthe same movement to occur with respect to the water piston 22 in theadjacent water chamber 14, which water piston 22 is also mounted on therod 18. In other words, manipulation of the hydraulic supply means toforce the hydraulic piston 20 in a first direction causes that force tobe transmitted to the water piston 22 by means of the connecting rod 18,resulting in the water piston 22 being forced in the first direction anequal distance.

The water chamber 14, as can best be seen in FIG. 3, comprises a waterinlet 24 through the housing 12. This section of the housing 12 ispreferably but not necessarily a machined, stainless steel manifoldblock. The water inlet 24 comprises an aperture 52 which opens in adownstream direction; this allows water to be drawn into the water inlet24 in an upstream direction, which assists in preventing the ingress andbuild-up of fines and methane gas. The water inlet 24 is also providedwith a check valve 36, comprising a stainless steel check ball 50, whichensures that water can be drawn into the water chamber 14 by means ofthe water inlet 24 but cannot be forced out through the water inlet 24.

The water chamber 14 also comprises a water outlet 26 which connects toa water exhaust tube 32 (see FIGS. 1, 2 and 3) extending downstream fromthe water chamber 14 through the horsing 12. As can be seen in FIG. 2, adownstream segment of the water exhaust tube 32 is provided with anexhaust check valve 34, comprising a stainless steel check valve insert54 and check ball 38. As was the case with the check valve 36, exhaustcheck valve 34 is to control fluid flow direction. While water can bedrawn downstream through the exhaust check valve 34, it cannot be drawnin an upstream direction. The downstream section of the pump apparatus10 that houses the exhaust check valve 34 and connectors 40 is providedwith a pin connector 56 for connection to a box connector 58 on thehousing 12 section containing the water and hydraulic chambers 14, 16.

The section of the housing 12 just upstream of the water inlet 24 andwater outlet 26 is provided with an O ring seal 60 and back-up ring 62.

The water chamber, as can be seen in FIG. 4, is provided with watercooling vents 64. This allows cooling water into the area of the rod 18on a single-acting configuration, but the water cooling vents 64 can beconverted for use with a double-acting configuration.

Referring to FIGS. 4 and 5, the pump apparatus 10 is also provided withvarious seals 72, a back-up ring 74, a wiper ring 76, wear rings 78, andan anti-extrusion ring 80. The hydraulic chamber 16 is also providedwith a stainless steel rod end gland 82 (with a built-in cushion), a rodend piston cushion 84, and an upstream end oil piston cap 86 (withbuilt-in cushion). The hydraulic piston 20 is provided with tapered endsso that, upon the hydraulic piston 20 nearing the end of its stroke,hydraulic fluid squeezes out of the space adjacent the tapered end andcushions the hydraulic piston 20.

The embodiment of the present invention is used as follows. When it isdesired to use the pump apparatus 10 to pump unwanted fluids such aswater out of a well, first hydraulic supply tube 28 is used to injecthydraulic fluid into the portion of the hydraulic chamber 16 downstreamof the hydraulic piston 20, driving the hydraulic piston 20 in anupstream direction. This movement causes the rod 18 to move in anupstream direction, causing the water piston 22 to also move in anupstream direction. Fluid is drawn through the water inlet 24 due to thepressure change inside the water chamber 14 when the water piston 22moves upstream, filling the area within the water chamber 14 downstreamof the water piston 22. Fluid cannot be drawn into the water chamber 14through the water outlet 26 due to the presence of the exhaust checkvalve 34.

To exhaust the fluid contained within the water chamber 14, hydraulicfluid is then injected through the second hydraulic supply tube 30 andinto the portion of the hydraulic chamber 16 upstream of the hydraulicpiston 20, driving the hydraulic piston 20 in a downstream direction.Forcing the hydraulic piston 20 in a downstream direction causes the rod18 to also move in a downstream direction, and the water piston 22accordingly is forced in a downstream direction. The downstream movementof the water piston 22 exerts pressure on the fluid within the waterchamber 14, which pressure is released by the ejection of fluid throughthe water outlet 26 and water exhaust tube 32. As the water inlet 24 isprovided with a check valve 36, the fluids cannot escape by the means.The fluids are then moved through the water exhaust tube 32 toward thesurface and out of the well (not shown).

While a particular embodiment of the present invention has beendescribed in the foregoing, it is to be understood that otherembodiments are possible within the scope of the invention and areintended to be included herein. It will be clear to any person skilledin the art that modifications of and adjustments to this invention, notshown, are possible without departing from the spirit of the inventionas demonstrated through the exemplary embodiment. The invention istherefore to be considered limited solely by the scope of the appendedclaims.

PARTS LIST

-   1 STAINLESS STEEL CHECK BALL—1⅞″ DIAMETER-   1A STAINLESS STEEL CHECK VALVE INSERT-   2 STAINLESS STEEL CHECK BALL— 15/16″ DIAMETER-   3 568-244 O'RING SEAL 90 DURO-   4 575-244T BACK UP RING-   5 568-246V O'RING SEAL 90 DURO-   6 575-246T BACK UP RING-   7 1¼″ NF LOCK NUT-   8 RDH45-5007 STAINLESS STEEL 1-PIECE PISTON w/MOLDED URETHANE-   9 PS1850-72 BRONZE FILLED PTFE SEAL w/RUBBER O'RING ENERGIZER-   10 568-222V SEAL w/VITON LOADER-   11 612T-050B NYLON WEAR RING-   12 HW1500V URETHANE WIPER RING-   13 DPU-37-3-75-62V HEAVY DUTY PISTON SEAL-   14 568-222V O'RING SEAL VITON-   15 612T-050B NYLON WEAR RING-   16 DURA BAR HYDRAULIC PISTON-   17 1⅛″ NF LOCK NUT-   18 1½″ STAINLESS STEEL ROD-   19 4½″ ID×5¼″ OD STAINLESS STEEL MICRO HONED TUBE-   20 OIL IMPREGNATED BRONZE WEAR RING-   21 STAINLESS STEEL ROD END GLAND w/CUSHION BUILT IN-   22 ROD END PISTON CUSHION-   23 BOTTOM END OIL PISTON CAP w/CUSHION BUILT IN-   24 WATER CHAMBER—COOLING BOTH WATER & HYD. ROD SEALS PLUS    LUBRICATING ROD-   25 WATER COOLING VENT-   26 STAINLESS STEEL SOLID MANIFOLD BLOCK-MACHINED-   27 U25-1-50-37BV ANTI-EXTRUSION RING 1½×2×0.070 GLASS FILLED TEFLON    0.475 GROOVE WIDTH

1. A pump apparatus comprising: a housing; a water chamber in thehousing; an hydraulic chamber in the housing; a rod member extending atleast partially into each of the water chamber and the hydraulicchamber; a first piston member mounted on the rod member and containedwithin the hydraulic chamber; a second piston member mounted on the rodmember and contained within the water chamber; hydraulic means foralternatively forcing the first piston member in first and seconddirections; fluid inlet means extending through the housing adjacent anend of the water chamber; and fluid outlet means extending through thehousing adjacent the end of the water chamber; wherein when thehydraulic means force the first piston member to move in the firstdirection, the second piston member is forced to move in the firstdirection, and fluid is drawn through the fluid inlet means into thewater chamber; and wherein when the hydraulic means force the firstpiston member to move in the second direction, the second piston memberis forced to move in the second direction, and fluid is forced throughthe fluid outlet means.
 2. The pump apparatus of claim 1 wherein thehydraulic means comprise: a first hydraulic tube in fluid communicationwith the interior of the hydraulic chamber on a first side of the firstpiston member; and a second hydraulic tube in fluid communication withthe interior of the hydraulic chamber on a second, opposite side of thefirst piston member; wherein when hydraulic fluid is forced through thefirst hydraulic tube, the first piston member is forced to move in thefirst direction; and wherein when hydraulic fluid is forced through thesecond hydraulic tube, the first piston member is forced to move in thesecond direction.
 3. The pump apparatus of claim 1 wherein the fluidoutlet means comprise a fluid exhaust passage within the housing.
 4. Thepump apparatus of claim 1 wherein the fluid inlet means and fluid outletmeans comprise check valves to control fluid flow.
 5. The pump apparatusof claim 1 wherein the fluid inlet means comprise an aperture opening ina downstream direction, such that when the fluid is drawn through thefluid inlet means into the water chamber, the fluid is drawn in anupstream direction to avoid undue fines and gas build-up in the fluidinlet means.